It's not a problem to just flash the AC card and a boarding pass for the other pier. I have never had a problem, most of the time they wouldn't even notice if your flight leaves from the other side, and if they do just say "Admiral's Club" and that's that.
Reclearing security can be no fun however. Still, those security lanes are so constricted and cramped that they often look "longer" than they really are. Usually even if the line reaches the top of the ramp it's still no more than about 10 minutes.